Buying and holding great stocks is the best way to consistently generate wealth over the long term. But finding the market's best stocks is easier said than done.

So to help get you started to that end, we asked three top Motley Fool investors to each pick a stock that they believe is poised to double investors' money. Read on to see why they chose Boston Beer (SAM -1.16%), YY (YY), and Magellan Midstream Partners (MMP).

Man in suit drawing a line chart indicating financial gains


Cheers to a great investment

Steve Symington (Boston Beer): Thanks to the strong execution of its fall seasonal program and encouraging business trends in its latest quarter, shares of Boston Beer are trading near a 52-week high right now. But the stock is also more than 40% below its all-time high set in early 2015, when growth in the burgeoning craft beer market began to slow amid increasing competition from both small and large brewers alike. Even now, Boston Beer's recent rebound has come despite the fact that its volumes still fell 4% on a year-over-year basis last quarter, as strength from its Twisted Tea and Truly Spiked & Sparkling varieties were more than offset by the relative underperformance of its flagship Samuel Adams and Angry Orchard brands.

That said, I think Boston Beer's latest trends for depletions -- a key industry metric that measures how fast its products travel from warehouses to consumer outlets -- show the company is learning how to more effectively navigate its crowded core market. Depletions fell 3.5% year over year last quarter, but are expected to turn a corner and climb in the low-single-digit range in the coming year. All the while, Boston Beer has been focusing on cost savings and operational efficiency initiatives that should help it emerge a leaner, stronger company when it's able to return Sam Adams and Angry Orchard to growth.

When that happens -- and unless Boston Beer is acquired by an opportunistic competitor before then -- I think the stock could easily be a double for investors who buy today.

One of China's live-streaming pioneers

Leo Sun (YY): YY is a Chinese provider of live video streaming services. It was one of the first movers in this growing industry, which Jefferies estimates could become a $6.4 billion industry by 2020. YY's platform consists of YY Live, which features music, entertainment, sports, and e-learning videos; and Huya, which features video gameplay streams.

YY monetizes those videos with virtual gifts, which users purchase for their favorite broadcasters. About 93% of YY's revenue came from its live video streaming business last quarter, with the remainder coming from its older online games, membership fees, and online advertising businesses.

Revenue rose 48% annually to $465 million last quarter, marking its highest growth rate in seven quarters. Its non-GAAP net income rose 47% to $96.1 million, and its GAAP net income jumped 59% to $95.6 million. Its live-streaming revenue grew 60% annually, mobile live-streaming monthly active users (MAUs) rose 37% annually to 73 million, and its paid users climbed 47% to 6.3 million.

Analysts expect YY's revenue and non-GAAP earnings to rise 38% and 41%, respectively, this year. However, investors should be aware of some potential headwinds -- which include competition from other platforms like Momo (NASDAQ: MOMO) and tighter government regulation of live-streaming apps.

YY trades at just 18 times trailing earnings and 15 times forward earnings -- making it an undervalued growth play in the arguably frothy Chinese tech market. If YY continues growing its revenue, earnings, and MAUs at its current pace, it could certainly double in the near future.

Energize your portfolio with this pipeline leader

John Bromels (Magellan Midstream Partners): The boring world of energy infrastructure isn't exactly a place you'd expect to find a company that could double your money in two years, but Magellan Midstream Partners did just that for its investors between 2010 and 2012 and again between 2012 and 2014. And all the while, it also paid a dividend. Shares peaked in 2014 as the energy price slump hit the industry, but they look like they're starting to recover.

Magellan is a pipeline operator, which means it charges oil and gas producers to move their products through its 9,700 miles of pipelines. This "toll booth" model helps Magellan keep making money regardless of how expensive or cheap oil and gas are.

In the past, Magellan has been able to grow by purchasing assets from other companies. But if domestic oil and gas production takes off -- which it will if energy prices continue to rise -- Magellan can start commanding a higher price thanks to increased demand. It also has more than $1 billion of high-return expansion projects in the works, all of which should come on line within two years.

Meanwhile, Magellan has more than doubled its dividend since 2012, and now yields about 5.4%, which will help investors recoup their money faster. It's not the most conventional pick to double your money, but if oil prices and domestic production keeps going up, Magellan investors shouldn't be surprised to see handsome returns.